Spectral indices in Eddington-inspired Born-Infeld inflation

TL;DR

This paper studies how Eddington-inspired Born-Infeld gravity modifies the spectral indices of quadratic inflation, showing that EiBI corrections improve agreement with observational data, especially regarding the tensor-to-scalar ratio.

Contribution

It provides a detailed analysis of spectral indices in EiBI gravity for quadratic inflation, highlighting the order of corrections and their observational implications.

Findings

EiBI corrections to spectral indices are of second and first order for scalar and tensor perturbations.

EiBI inflation suppresses the tensor-to-scalar ratio, aligning well with observational data.

Quadratic inflation in EiBI gravity remains consistent with current cosmological observations.

Abstract

We investigate the scalar and tensor spectral indices of the quadratic inflation model in Eddington-inspired Born-Infeld (EiBI) gravity. We find that the EiBI corrections to the spectral indices are of second and first order in the slow-roll approximation for the scalar and tensor perturbations respectively. This is very promising since the quadratic inflation model in general relativity provides a very nice fit for the spectral indices. Together with the suppression of the tensor-to-scalar ratio EiBI inflation agrees well with the observational data.